1. Field of the Invention
The present invention relates in general to integrated circuits and in particular to voltage level shifting circuits, and methods and systems using the same.
2. Description of the Related Art
Sophisticated design and fabrication techniques are rapidly making practical systems-on-a-chip a reality. In turn, a broad range of personal and commercial hand-held appliances can be constructed which embody a high degree of functionality. These appliances include personal digital assistants, personal digital music players, compact computers, point of sale devices, and Internet access devices, to name only a few of the possibilities.
A number of factors must be addressed when designing a system-on-a-chip. Among other things, the device must be capable of interfacing with a broad range of input/output devices which may be required to support various potential user-defined applications. Moreover, the device must be power efficient while operating at high clock speeds. Additionally, this device should have a large address space to flexibly support a range of possible memory configurations and sizes.
A level shifter is disclosed according to the inventive concepts for shifting a logic high voltage of an input signal from a lower voltage to a higher voltage. The level shifter includes a latch for storing a bit of data and has an output for driving a stored logic high bit at the higher voltage. A data node is coupled to a source of the higher voltage and an input of the latch. Voltage control circuitry selectively gates the input signal received at the lower voltage with a bit of data stored in latch and selectively pulls down the voltage at the data node in response.
Circuits, systems and methods embodying the principles of the present invention have substantial advantages over the prior art. Among other things, level shifting can be performed on any input signal which exceeds the threshold voltage of the selected gating transistors. Moreover, different voltage supplies can be used for driving signals at the higher voltage plane. The implementation of the inventive concepts does not require complex circuitry or complicated switching schemes.